The present invention relates generally to a method and apparatus for constructing a pontic or pontics to fill an edentulous space adjacent to existing teeth or between two existing teeth and, more particularly, is directed to a method and apparatus for making a pontic or pontics in situ, with minimal adjustments, in one visit.
The formation or fabrication of a dental bridge to span a gap between two teeth, with one or more pontics, or to replace a missing tooth using a cantilevered pontic applied to one or more teeth, is well known in the art. The most common method of replacing a missing tooth or teeth is termed fixed coverage. Generally, the tooth or teeth adjacent to the missing tooth or teeth are ground down, and this usually requires anesthesia. Thereafter, an impression is taken of the missing tooth or teeth and the adjacent teeth by use of dental impression trays. An interim plastic dental prosthesis or bridge is then usually formed to cover the prepared teeth. This generally completes the end of the first visit with the dentist.
The impressions are then sent to a laboratory, where a set of model teeth are formed from the impressions made with the impression trays. A bridge framework is constructed at the laboratory to fit over the adjacent teeth and to provide a false tooth or teeth (pontic(s)) between the teeth, from the impressions. This prosthesis framework, or individual copings, is sent back to the dentist, and the patient then, during a second appointment, has the dental framework or copings tested for fit to the ground down teeth. If the framework or copings of the future dental prosthesis does not fit properly, the above procedure may have to be repeated.
Once the dentist gets to the next stage, either with the directly cast framework or after soldering and connecting copings to create a well fitting framework where it is determined that the framework fits properly, the bridge framework is returned to the laboratory for the application of proper tooth color and returned to the dentist for bite adjustment. Once the bite is ground in, the bridge is returned to the laboratory for final glazing and the like. If the final tooth color is wrong, the bridge may have to be sent back to the laboratory for an additional adjustment.
As a result of the above procedure, the patient may experience four to six visits at the dental office to obtain the fixed bridge, at a considerable inconvenience and cost to the patient.
Although various new products continuously appear on the market, utilizing, for example, newer cements or composites for securing the dental prosthesis to the teeth, multiple procedures are still required which take more than one visit.
Another method of forming a dental prosthesis between two teeth is described in U.S. Pat. No. 3,641,670. According to the method described therein, a groove is formed in the occlusal surfaces of the two teeth, facing each other. A bar traverses the edentulous space between the two teeth and the ends are secured within the grooves formed in the teeth. Thereafter, a paste-like filling material is inserted into a hollow tooth mold, and the tooth mold is forced over the bar such that the bar supports the tooth mold. Thereafter, the paste-like filling material is permitted to harden to form a solid tooth structure which is bonded to the bar. The bar, in turn, is cemented within the grooves in the teeth. Then, the tooth mold is removed, revealing the hardened tooth structure that has been formed.
With this system, however, it is extremely difficult to obtain accurate fitting of the formed tooth with respect to the gum surface (or gingiva). As a result, a large space remains between the lower surface of the formed tooth and the gum surface, which can trap bacteria laden and decomposable material generally responsible for tissue irritation and decay of adjacent teeth.
Other U.S. patents which disclose the use of transverse bars or the like between adjacent teeth, for supporting a dental bridge, are U.S. Pat. Nos. 339,958; 446,769; 1,211,494; 1,262,705; 3,369,509; 1,376,645; 1,649,905; 1,688,621; 1,738,460; 2,028,882; 2,213,964; 2,573,804; 2,635,338; 2,672,686; 2,835,034; 3,091,032; 3,442,015; 4,163,318; 4,360,342; 4,380,432; 4,431,415; 4,445,862; 4,457,714 and 4,474,499.
In regard to providing a screw-threaded adjustment of a false tooth, attention is directed to U.S. Pat. No. 3,787,975. However, adjusting the height of a tooth in accordance with the teachings of this patent is extremely complex as is the device for achieving this end.